Apparatus for the production of music



p 4 B. F. MIESSNER APAMTUS FOR THE PRODUCTION OF MUSIC File'd March 29,. 192W 3 Sheets-Sheet 1 IN VEN TOR.

Sept. 24, 19402 B. F. MIESSNER APPARATUS FOR THE PRODUCTION .OF MUSIC Filed-llarch 29, 19s? a sheets-sheet 2 IN V EN TOR.

t 1 5 km Bmh M w] a Sept. 24, 1940.

3 Sheets-Sheet 5 Filed March 29. 1937:

IN VEN TOR.

I Patented Sept. 24, 1940 UNITED STATES PATENT OFFICE Benjamin F. Miessncr, Millburn, N. J., assignor to Miessner Inventions, 1110., Township of Millbnrn, N J a corporation of New Jersey Application March 29, 1937, Serial No. 133,571

17 Claims.

This invention relates to the production of music, and more particularly to that production by the generation of electric oscillations and the translation thereof, after their suitable control,

into acoustic oscillations. My invention has especial reference "to instruments wherein the generation of oscillations is performed by continuously operatinge. g., revolving-generators.

Instruments of this character fall generally w into two classes: one wherein individual generators are employed for the generation of substantially sinusodial oscillations of various irequenoies, each output tone of the instrument being compounded from the sinusoidal outputs of a plurality of these generators which are harmonically related to each other in frequency; and

the other wherein individual generators are employed for the generation of oscillations which are complex and themselves represent musically useful tones. My invention has especial reference to the second of these classes of instrument.

it is an object of my invention to provide a generally improved musical instrument of the class described.

It is another object to provide improved generating means for such an instrument.

It is another object to providejmproved control means iorsuch an instrument.

it is another object to relate the generating means with the control means in improved mannor.

Another object is to increase the flexibility of the instrument in respect of the available out put tone qualities.

A general object is to provide a musical instrument with continuously acting generators which is particularly simple and at the same time renders available a wide variety of output tone qualities.

A particular object is the provision of an improved keying arrangement for connection with the outputs of the generators.

Other and allied objects will more fully appear from the following description and the appended claims.

In the description reference is had to the accompanying drawings, of which:

. Figure 1 is a partial elevational View of an instrument embodying my invention in one form, various portions thereof being shown schematically;

Figure 1a is a cross-sectional view taken along the line lala of Figure 1, the line l--l in Figure 1a indicating the relationship to the latter figure of the corresponding portion of Figure 1;

Figure 2 is a partial plan view of an instrument embodying my invention in a modified form, various portions thereof being shown 5 schematically;

Figure 3 is a partial front elevational view, taken with certain elements omitted, of an'instrument embodying my invention in a further modified form; and 10 Figure 3a is a principally side elevational view of the instrument of Figure 3, showing various additional elements schematically; the lines Biz-30, and 3-3 in the respective Figures 3 and 3a indicating the planes from which the other 15 figure is taken.

According to my invention I employ, electrically interposed between a set of playing keys and an electrical or electro-acoustic load which may he one or more typical amplifier-loudspeaker 29 combinations, continuously revolving generating means for a number of series of complex oscillations; the generating means are arranged so that these several oscillation series for each one note are of mutually similar fundamental 5 frequency but of predeterminedly difierent instantaneous amplitudes, which last characteristic enables an effective control over output harmonic structure (e. g., tone timbre) by differential control of the response of the load to the several 39 oscillation series. In carrying out my invention a wide variety of embodiments are available; and i shall first review several examples of forms, arrangements in an instrument, types, and manners oi interposition (between keying and load 35 means) of the generating means; and of control functions and control methods. Thereafter I shall show and describe some purely typical embodiments wherein the several specifically mentioned forms, arrangements, types, etc. are variously incorporated. It will be understood, however, that I do not intend these examples in respect of any characteristic to be taken as exhaustive of the permissible variations of my invention in that particular respect.

I may particularly mention two basic forms. of generating means which may be employed to meet the specification which I have laid down above. A first comprises two or more generators per note yielding complex oscillations of identi'. cal fundamental frequency but of respectively different waveform; such a plurality is typified by a plurality of sound tracks per note; permissibly of course on the same revolving member, each with its own pick-up. The second comprises a single complex-oscillation generator per note with a plurality of output means suitably arranged to meet the above specifications; this is typified by a single sound track with a plurality of pick-ups disposed therealong with non-integral cyclic separations from each other-i. e., separations which are not integral multiples of the length of a fundamental cycle in the track. And of course both these forms may be simultaneously employed when desired.

In respect of physical arrangement of the generating means in an instrument, at least two arrangements are available. According to a first, all generation for each one note occurs in one place or locality, the multiple generators or multiple output means for each note being desirably made to have a mutual relationship cyclicly corresponding with the similar relationship between like elements for each other note. According to the second, a group is formed of one generator each for all notes, and another group is formed of another generator each for all notes, and so on; again the several generators for each note are desirably made to have the mutual relationship abovementioned, but in this instance it may be more convenient to think of equivalent relationships between generators for different notes in one generator group being held similar to those between generators for corresponding notes in the other generator group.

A wide variety of types of generators are obviously available, specific examples being magneto-e1ectric; capacitive (the capacities being energized by an inaudible frequency current, typically of zero frequency and in such case direct); and photo-electric.

The electrical interposition of the generating means between keying and load means also may be variously carried out. For example, the generating means may be serially interposed between the keying and load means, the keying means then typically forming a switching means for eifectively connecting the generating and load means. On the other hand, the output of the generating means may be permanently connected with the load means, the keying means for example controlling the activation, or input of activating energy, to the generating means.

The control functions which I may perform on the several series of oscillations, so that the harmonic structure of their mutual superposition in the load means may be eifectively varied, are several. I may control the relative amplitudes of the several series; or I may control the relative phases, typically but not limitatively by reversing means; or I may of course control both amplitudes and phases. I further may control the phases in intermediate degree-i. e., by shifts less than the lilo-degree shift incident to reversaltypically in a progressive manner.

For control methods I may employ any one or more of at least three general systems: an electrical control operating directly on generating means output, a control of generating means activation, and an immediate mechanical control of the mutual relationships of the elements oi. the generating means.

Having so described my invention generally, I may refer specifically to Figure 1. In the instrument of this figure there are employed jointly both the abovementioned forms, the first-mentioned arrangement, the magneto-electric type, and the serial interposition, of the generating means; and amplitude and phase control, by electrical means operating directly on the output of the generating means, of the several oscillation series. In this figure as the keying means I there have been shown a white and an adjacent black key, la and lb respectively, it being of course understood that a key for each note of the instrument will be provided. Each of these keys may be provided with a plurality of switch poles, shown for key la as the four poles 2a, and for key lb as the four poles 217. Each key is arranged so thatv its depression will close its several poles against a common contact bar or rail 3; a particular structure of poles and contact rail has been illustrated more in detail in Figure la and will hereinafter be more detailedly described. The load means in Figure 1 has been simply illustrated as a cascade which may typically comprise amplifier ll, potentiometer or other volume control l2 (operated if desired as by foot-pedal l2), further amplifier l3, and loudspeaker or other electro-acoustic translating device ll. The contact rail 3 has been shown connected to one terminal of the amplifier, the other terminal of the amplifier being for example connected to some reference potential conveniently hereinafter referred to as ground. The generating means, next detailed, is shown appropriately connected between the several switch poles and ground.

The generating means illustrated in Figure 1 comprises a plurality (by way of simple example, two) of discs for each note of the instrument, of magnetic material and having mutually different complex waveforms, but of the same number of cycles, cut in their peripheries. The discs for the first note (i. e., of key la) appear as Ila and 22a; those for the second note appear as Zlb and 221), it being understood that the waveform cut in Zlb is similar to that in 2la, and that in no similar to that in 22a. The group of discs for each one note, together with an appropriate gear, may be secured on a respective shaft; for example, the disc Zla may be secured on a shaft 24a, the disc 22a to the same shaft somewhat forward of Zla, and the gear 23a secured to the same shaft still forward of 22a-and b elements in correspondence on the shaft 24b, etc. The shaft 24a may be driven coincidentally with the shaft 24b through any suitable complex or simple coupling means, typified by the gear 25 interposed between gears 23a and 23b, of course in suitable speed relationship for their respective notes established as by choice of the numbers of teeth in the several gears (in view of the numbers of cycles in the waveforms cut in Hat-22a on the one hand and 2lb22b on the other, as will be understood). Both shafts 24a and 24b are driven coincidentally with those for still other notes (not shown) through any suitable coupling means, typified by gear 26 engaging the gear 23b.

Generating means of the first form mentioned above are completed in the instrument of Figure 1 by the association, with all the discs (e. g., 2la, 22a) for the first note, of respective magnetic pick-ups (e. g., 21a, 28a) with all the discs (e. g., Ilb, 22b) for the second note, of corresponding pick-ups (e. g., Zlb, 28b); etc. The

I cyclic mutual relationships between these two pick-ups in the case of each n0te-e. 8., that between 21a and 28a, that between 21b and 28b, etc.are made mutually similar; for example, if in the case of the first note the pick-up 28a is opposite a maximum diameter peak of the waveform of disc 22a 'at the same instant that pick-up 21a is opposite a maximum diameter peak of the waveform of disc I la, then a similar relationship I} 2,215,708 is observed in the case of the corresponding (1)) elements for the second note, etc. The pick-ups preferably have relatively sharp pole-tips; and they are held stationary, by any suitable means not necessary to show, with their pole-tips in quite close spaced relationship to the paths of the maximum diameter peaks of their respective discs.

By way of example of a simple electrical interconnection of the several pick-ups and connection thereof with the keying means, appropriate to the simple keying means above described and to a simple control system, I have shown each pick-up as provided with a center-tap, ineach case designated by the designation of the respective pick-up together with a prime mark. The center-taps, 21a and 28a, of the two so-far described pick-ups for the first note are respectively connected to two of the poles 2aon key la; correspondingly the center-taps 21b and 28b for the second note are respectively connected to two of the poles 21) on key lb, etc. corresponding pick-ups 21a, 21b, etc., for the several notes may be connected in parallel across a potentiometer 21 having the grounded variable contact 21'; and the mutually corresponding pick-ups 28a, 281), etc., for the several notes may be connected in parallel and across a potentiom- 'eter 28 having the grounded variable contact 28' it being understood that a separate such potentiometer will be employed for each ofthe discs which are used in the assembly for a single note.

It will be understood that in the operation of theapparatus the pick-ups 21a, 21b, etc., will develop alternating potentials of mutually similar waveforms and of the fundamental frequencies of their respective notes; and that at their center-taps 21a, 21b, etc., these alternating potentials will appear as potential differences from ground, of both amplitude and phase (in respect of reversal) regulable simultaneously for all notes by the position of contact 21'. Obviously upon depression of any one of the keys (causing its respective poles to touch contact rail 3) this so regulated potential for that note will be applied to the input of the load means (e. g., input of H).. Quite correspondingly at the center-taps 28a, 28b, etc., there will appear alternating potential differences from ground. These will be of waveform similar to one another but different from that of the potentials at 21a, 2110', etc.; they will of course be regulated in amplitude and phase by adjustment of contact 28'; and this so regulated potential for any note whose key is depressed will of course be applied to the input of the. load ,means simultaneously with the potential of different waveform discussed above-in other words, an individually regulated output corresponding to each different waveform for which a disc is provided in the single-note assembly will be simultaneously applied to the load means upon key despression.

The waveforms may be chosen to be thoroughly distinct-respectively representing, for example,

quite distinct orchestral instruments-so that their mere alternate use (all but one of the contacts 21', 28, being. centrally adjusted at a time) provides a plurality of distinct output timbres.

But by the simultaneous use of more than one, with relative. amplitudes fully regulated by the contact settings-rand still further, with relative phases also so regulateda very wide timbre variation is readily made available. And by virtue of theuniform maintenance of cyclic relationships discussed above, the effects of all pos- The mutually sible combinations of potentiometer contact adjustments on the several different notes will be maintained uniform.

The second form of generating means mentioned above was that of a single complex waveform generator with a plurality of output means --for example in terms of the Figure 1 embodiment, a single disc for each note with a plurality of pick-ups associated therewith-the output means being separated from each other by nonintegrai cyclic displacements or separations. In such a case these several pick-ups of course develop potentials of mutually similar waveform; but because of the non-integral spacing there is provided a phase displacement between their several developed potentials, which for each partial component of the oscillations is effectively different, so that varying the -mutual relationships (amplitude and/or phase) between the several developed potentials will result, when they are combined, in a potential of varying waveform.

So in Figure l I have illustrated a second pickup 29a associated with the disc 2 l a and separated from pick-up 21a by a whole number (as shown, 2), plus a fraction of (e. g., 2.3) times the length of a cycle in disc 2|a; correspondingly there will be associated with disc 2lb a second pick-up 28b separated from pick-up 21b by a whole number, plus a like fraction of 1%, times the length of a cycle in disc Zlb; etc. These pick-ups may have respective centertaps 29a, 29?), etc., each wired to an otherwise unused pole (2a, 2b, etc.) of the corresponding key; and at their extremities they will be connected in parallel and across a potentiometer 29 having the grounded variable contact 29'. It will be understood that adjustment of potentiometer contacts 21 and 29' (assuming contact 28' centered to eliminate the effect of pick-ups 28a, 282), etc.) will provide a timbre variation in manner which, excepting that the potentials being combined originate in similar waveform, is quite analogous to the timbre variation effected, as explained above, by contacts 21' and 28'.

Of course still wider variations are possible from the use of all three contacts 28', 21 and 29'. And there is further possible the addition of a second pick-up (e. g., 30a, 30b) to each of the discs 22a, ZZb-for example at respective separations from 28a, 28b, of a whole number, plus the fraction of /2, times a cycle length on the respective disc-and the connection of the center-taps 30a, 30b of these pick-ups each to an otherwise unused pole (2a, 2b) of the corresponding key, together with the paralleling of these added' pickups and their, connection across a potentiometer 30 having the grounded variable contact 30'. Potentiometer contacts 28 and 30' then provide a timbre variation by combinations of potentials from the single discs 22a, 22?), etc.; and by using all four illustrated potentiometer contacts 21', 2 8, 29', 30', extremely wide timbre-variation facilities are provided.

While the switching apparatus included in the keying means of Figure 1 may be of any multipole, common-contact variety, I have shown in Figure 1a a view of a form which has advantages in reducing tendencies toward key-click in the output sound from the instrument, and is of very simple form in view of the common nature of the rail 3 to all the notes. Of course it will be understood that key-click may be minimized by apt choices of relative impedances of the pick-ups, potentiometers, and amplifier II; but this further reduction is a still further benefit. According to this form, the poles (e. g., 2b) are formed of relatively fine, resilient wires such as phosphor bronze, beryllium copper, suitably plated steel or the like; and they are stretched under very mild tension underneath the key, as between the forward insulating block 4 secured directly to the bottom of the key, and the rear insulating block 5 correspondingly secured but through the medium of rearward-biasing spring 5. The contact rail proper, or 3, of conductive material, may be disposed spacedly below the forward portions of the wires; but it may be extended rearwardly by a wider rail 1 secured to it, of less perfectly conductive or actually insulating material, the top of rail 1 being preferably slightly convex. Over the top of the joined rails I and 3' may be coated a carbon or graphite resistance layer 8 whose top is slightly convex, and which may taper to negligible thickness on top of the contact rail proper 3' (one method of applying the layer 8, to which however no limitation is intended, being by the successive application of coatings of colloidal graphite solution).

The spacing of the elements and curvature of the top of 8 is such that as the key is depressed the pole wires 21) first touch the rear edge of the layer 8; it will be understood that in view of distance the electrical resistance from here to the conductive rail proper is very high and, it being serially in circuit, negligible key-click" is produced at this instant. Further key depression causes the pole wires to flex gradually and to come into contact progressively with more forward surface 8 portions, lowering the resistance of the contact as 3' is approached, and finely contacting with the thin, and therefore negligible-resistance, layer portion immediately over 3. In other words the pole wires warp" longitudinally into final full contact with the top of layer 8; and since there are no discontinuities following the initial unimportant one, there are no further opportunities for keyclick.

Preferably, of course, the stiifnesses of the pole wires and of spring 5 are made low enough, relative to that of the usual upward key-biasing spring 9, so that the latter greatly preponderates in establishing the resistance of the key to downward movement about its pivot l0, and hence in establishing the feel of the keys to the player.

Figure 2, by way of alternative example, illustrates an instrument embodying the first abovementioned form, the first abovementioned arrangement, the capacitative type, and the second abovementioned interposition, of the generating means; and amplitude and phase control of the several oscillation series by electrical means operating on those series after mutually independent amplifications of the latter. In this instrument the generating means may include a plurality of cylinders-for example, one for each of the twelve semi-tones of the octaveof which two are illustrated as Ha and Nb respectively. These cylinders may be secured on respective shafts 42a and 42b, each of which may in turn be suitably journalled at each end of its cylinder-lndicated by the journalling of shafts 42a and 42b in respective standards a and b to the left of the cylinders. The cylinders may be driven in suitable mutual speed relationshipsfor example, cylinder llb at substantially forms for each octave of that note.

times the speed of cylinder Ha, etc-through the medium of any suitable coupling means, typified by gears 43a and 43b on the respective illustrated shafts and gears 45 and 45 engaging those gears.

The cylinders, for reasons which will hereinafter be apparent, are desirably formed of insulating material or provided with an insulating surface; and on each may be carried a plurality illustrated as two-of sound tracks of mutually distinct waveform for a first note, and for example a like plurality of corresponding wave- Thus on cylinder Ha I have shown mutually different waveform tracks "a and 48a for a first note in a first (e. g., the lowest) octave of the instrument, and mutually different waveform tracks 49a and 50a for the same note in a second octave; and on cylinder lb corresponding tracks 41b and 48b for an adjacent note in the first octave, and corresponding tracks 49b and 50b for that note in the second octave. The cyclic relationship existing between tracks 41a and 48a is of course observed in the case of all other groups of tracks for any one note.

To show the indifference of my invention to the manner of scanning of the tracks by the pick-ups, and having shown variable-distance" scanning in Figure 1, I show the tracks of Figure 2 arranged for variable area" scanning. Accordingly each track may be formed of a conductive element secure with respect to the appropriate cylinder and having a surface parallel with (for, example slightly raised from) the main cylinder surface; the track represents its particular waveform by the variations of its width (i. e., dimension longitudinally of the cylinder) from point to point in its length around the cylinder. The pick-ups have been shown by way of example as very thin metal electrodes or vanes, each held stationary by any suitable insulating means (not shown) so that its plane if projected would contain the cylinder axis and so that its inner edge is in very slight spaced relationship to the surface of the respective track. A pick-up for each illustrated track has been shown and designated by a number higher in each instance by 4 than that of the respective track, and with a corresponding letter.

All the pick-ups associated with tracks of a first waveforme. g., 5| a, 53a, 5lb, 53b-are connected to a common conductor system 55 and therethrough to the top extremity of a high resistance 5!, of which the bottom extremity may be grounded; all the pick-ups associated with tracks of a second waveform-e. g., 52a, 54a, 52b, 54b-will be correspondingly connected to a common conductor system 55 and therethrough to the top extremity of a high resistance 62, of which the bottom extremity may be grounded, etc. The function of each pick-up is to develop, across the high resistance to which it is connected, an alternating potential corresponding in waveform to that of the track associated with that pick-up; this the pick-up does by virtue of the variations, according to that waveform, of the capacity between it and the track. It may here-be noted that it is desirable to minimize capacity between the conductor system 55, with pick-ups thereto connected, and the conductor system 56 and its pick-ups; and to such extent as this minimization is not inherently provided by arrangement in any given case, it should be provided by shielding. I have illustrated this schematically by the vanes 3| interposed between adjacent pick-ups, and continuation shielding 38 interposed between the conductor systems-the grounding of all this shielding means being schematically indicated by the grounding of 38.

perform its just described function it is necessary to impress a potential across the capacity between it and its associated track, through a high resistance which may be that (6| or 62) already mentioned; this potential, as early above pointed out, may if desired be a direct potential. In this instrument I have shown this impression as controlled by the keying means. Accordingly there may contact with each track a stationary brush or other contact means, designated in each instance by a number higher by 10 than that of the respective track, and with a corresponding letter; and all of the brushes for each one note may be connected to the pole of a respective singlepole, double-throw switch, shown as 6311 for the first note of the first octave (i. e., for tracks 41a, 48a), as 63b for the second note of the first octave, as 65a for the first note of the second octave, and as 65b for the second note of the second octave. The upper-throw contacts of all these switches may be connected in common to ground, and the lower-throw contacts in common to the one terminal of a battery or other high voltage source 61, of which the other terminal is grounded. Keys 64a, 64b, 66a, 66b are shown associated respectively with the poles of the four switches just mentioned, so that each controls a respective switch and therethrough the activation of the several pick-ups for the respective note. respective tracks at ground potential, so that no potential is impressed across the respective trackto-pick-up capacities; but upon and throughout the continuance of depression of the key for any note, the resulting throw of the associated switch establishes the tracks for that note at a potential different from ground by that of source 61, and this potential obviously is impressed across each of the track-to-pick-up capacities for that note through the respective high resistances GI and 62.

when a direct potential is used in the activation of the pick-ups, it is. desirable that there be included, in each connection from brushes to a respective switch pole, a time delay system 68. Each suchsystem may comprise for example two series resistances 69 and H, and two shunt condensers l0 and I2 shuntedfrom the brushward extremities of the respective resistances to ground. The effect of this system is to render each change of potential of the tracks of finite rather than infinite speed; this provides a tone attac and release agreeably simulating that of an average conventional wind instrument, for

example.

The instrument being in operation, it will be understood that upon and'during continuance of depression of the key for any note, alternating potentials of the fundamental frequency of that note but of respectively different waveforms will appear across the several resistances GI, 62. These potentials, or several series of oscillations, may if desired be passed into a di- The switches may normally establish the lated ratios; according to known practise.

transformers 8i and 82 before being fed into a control system 83. This system may comprise potentiometers 85, 86, respectively shunted across the transformer secondaries, and provided with respective center-taps 85', 86','and with respective fully variable contacts85", 88". A series circuit may-be formed of those portions of the several potentiometers which lie in each case between a center-tap and a movable contact, and this circuit may-be connected across further load means such as ll'-l2l3--ll of Figure 1for example in the illustrated case, center-taps 85' and 86 may be connected together, and variable contacts 85'f and 86" connected to the amplifier II. The full variability of relative amplitudes, and of relative phases (in respect of reversal), of the several oscillation series will be apparent.

It will be understood that the omission, from association with each track, of asecond or further pick-up (analogous to the pick-ups 29a, 30a, 'etc., of Figure 1) is by way of example only. It

will also be understood that the use of partially divided load means for the several oscillation terposition of the generating means; and ampli tude control over oscillation series by control of activation, phase control thereover in respect of reversal by control or output, and phase controlthereover in respect of intermediate displace-f ments by a mechanical control of 'elements, of the generating means.

In these figures there will be seen a disc II, for example which is generally opaque and which may bear a plurality of concentric tracks in the nature or translucent portions; two central or intermediate tracks have been illustrated as "Ba and I091), and two respectively adjacent ones (more inward and more outward, respectively), have been indicated as I09 and I090. The disc III may bear as many of these tracks as is found practical-in the limit, one for each note of the instrum'entof appropriately different fundamentally frequencies but all similar in waveform, a typical number of tracks being much larger than itis possible properly to show in the drawings. It will be understood that there are preferably, in even the lowest frequency track, a relatively much larger number of cycles than it is possible to show in the drawings,.in order that the usual inter-note frequency ratios may be fairly approximated by the ratios of numbers of cycles 'in the several tracks; there will further be understood as permissible the slight pinching or expanding of one or'more cycles in each track to cause the prepondrateportions of the several.

tracks to contain cycle-lengths of accurately to- The disc llll may be securedtoa suitably journalled shaft M3 for rotation. 2Behindthe disc may be provided illuminating nie'ansfor the tracks; arranged in any known .manner' to permit control of the track or tracks, illuminated at any instant; and purely by. way of example I haveindicated a plurality'ot'lamps-(one for each track) by the showing of lampjsf-lt'sc and '1 lit for the tracks lllfla and I092) respectively, the lamps being heldin a suitable'cell structure 101 appropriately to localize their light outputs, a will be understood.

In front of the disc may be provided a shield III with narrow slit means in substantial juxtaposition to the several lights; for simplicity I have indicated the lights as in alignment radially of the disc, and the slit means as a single continuous slit H3. Still forward of the shield Ill may be provided a condensing lens II5 for the concentration of light from the several tracks (as they pass the slit) onto a photo-electric cell III. It will be understood that when any track is rendered active-in this case by lighting of the respective lampthe varying width (i. e., dimension radially of the disc) of the track will cause a variation of light reaching the cell, in accordance with the waveform of the track. The system so far described is intended as a complete generating means for an instrument for the production of tones of a single waveform; obviously the disc IOI may be pluralized if necessary for the provision of space for a sufficient number of tracks, and other changes may be made according to principles well understood in the art.

I duplicate this system by one or more others-- which duplication I have illustrated in the figures by a disc I02 and various portions thereof and elements associated therewith, designated in each instance with a number higher by one (1) than those already detailedsubject to the exception that the tracks IIOa, Il0b, etc., of the disc I02, while similar to each other in waveform, are of waveform distinct from that of the tracks in disc MI. The disc I02 may be driven at the same speed as the disc IIlI by any known a means, as I have schematically indicated by the provision of gears I03 and I04 on the respective shafts I03 and I04, and the mutual coupling and joint driving of these gears by the gear I00, on shaft I00 driven in any suitable manner. (Excepting for the difference in waveform of the tracks, the discs IN and I02 should be quite identical-i. e., they should be capable of being superposed in some relative position such that the beginning of all cycles in all tracks in the one disc will simultaneously lie directly over the corresponding ones in the other-and they are so secured on their respective shafts, and those shafts so coupled through the gears I03, I00 and I04, that this full correspondence between the discs is maintained at all times as to track portions respectively passing the slit I H and the slit H3 (the latter being in its mean or illustrated position).

I simultaneously render active the corresponding tracks in the several generating systems. This I may do by paralleling the leads I050 and I060 to one side of each of the lamps I05a and Mia. and leading the paralleled connection to a switch IIQa; by paralleling the leads I05b' and I06b' to one side of each of the lamps I05!) and N611 and leading the paralleled connection to a switch I ISb; etc. These switches are closed by depression of the respective keys I200, I201), etc.; when closed they connect the respective paralleled leads to a terminal of battery or other current source I 2i. The cell structure I01, to which the other sides of the contained lamps may all make contact, may be connected through a voltage-selecting switch I23 to any one of a plurality of different voltage points in the source I2I; correspondingly the cell structure I08, to which the other sides of the therein contained lamps may all make contact, may be connec d through a voltage-selecting switch I24 to any one of the same plurality of different voltage points. Obviously by virtue of switches I23 and I24 the relative degrees of activation of any two corresponding tracks are controlled, thereby controlling the relative amplitudes of the two different-waveform photo-cell outputs, from Ill and II! respectively.

The output from photo cell I I8 has been shown passed through a phase-reversing switch I25, whereby the relative phases of the photo-cell outputs may be controlled, in respect of reversal. I further show the two cell outputs connected across respective potentiometers I21 and I28, and the connection of variable portions of these potentiometers in series, for further relative amplitude variation between the photo-cell outputs, or series of oscillations. Load means, such as III2--I3-I4 of Figure 1, may be connected across these several variable potentiometer portions.

If, beside obedience to the specifications abovementioned, the tracks in each disc are all made (as illustrated in the case of those shown) to have in all their normal cycles identical cycle-lengths, I may additionally provide a satisfactory intermediate phase-shifting control. This I have illustrated by the support of shield III, instead of rigidly, to a rod I25 which may he slid slightly to the right or to the left in standards I30; this operation slightly moves the slit II3, so that it is uniformly advanced or retarded relative to all the waveforms moving therebehind. The cycle length being small, advancements or retardations up to a half cycle entail extremely small rod and slit movements, which have no sensible distorting efiect on the waveforms from even the smallest diameter tracks; and for precise adjustmentwithin this useful range I have shown the rod I29 leftwardly biased, as by spring I 3|, against the point of a screw I32 finely adjustable (as by knob I33) in standard I34.

It will be understood that in the various figures the dimensioning has been exaggerated in many instances in the interest of clear illustration; likewise, that the illustrated relationships of the maximum peaks of mutually associated waveforms, to each other and to associated pick-up means, are purely illustrative and in no way intended as limitative.

It will be appreciated that broadly the con trol which I effect over several series of oscillations is a differential one-i. e., it consists in more than a mere eiiective switching on and off, to and from the load, of the individual oscillation series. Where possible, the control is also desirably progressive-not in the sense of necessary complete continuity, but rather of the availability of at least a plurality of progressive settings, for a plurality of progressive responses of the load.

As to the generators, I use the term revolv-' I claim:

1. In a musical instrument including key means and oscillation-responsive load means: a plurality of continuously revolving generating means for respective notes of the musical scale, electrically interposed between said key and load means, each generating means comprising a plurality of devices for producing a respective plurality of complex oscillation series of the same fundamental frequency but of predeterminedly different instantaneous amplitudes, said devices in each said generating means having mutual cyclic relationships similar to those of said devices in each other said generating means; and control means, effective for a plurality of notes, for varying the response of said load means differentially'with respect to the several said oscillation series.

2. In a musical instrument including key means and oscillation-responsive load means: a plurality of continuously revolving generating means for respective notes of the musical scale, electrically interposed between said key andload means, each generating means comprising a pinrality of devices for producing a respective plurality of complex oscillation series of the same fundamental frequency but of mutually displaced phases, said devices in each said generating means having mutual phase. relationships similar to those of said devices in each other said generating means; and control means, effective for a plurality of notes, for varying the response of said load means differentially with respect to the several said oscillation series.

3. In a musical instrument including key means and oscillation-responsive load means: a plurality of continuously revolving generating means for respective notes of the musical scale, electrically interposed between said key and load means, each generating means comprising a plurality of devices for producing a respective plurality of harmonically distinct oscillation series of the same fundamental frequency, said devices in each said generating meanshaving mutual cyclic relationships similar to those of said devices in each. other said generating means; and control means, effective for a plurality of notes, for varying the response of said load means differentially with respect to the several said oscillation series.

4. In a musical instrument including key means and oscillation-responsive load meansz' a plurality of continuously revolving magneto-electric generating means for respective notes of the musical scale, electrically interposed. between said key. and load means, each generating means comprising a plurality of devices for producing a respective plurality of complex oscillation series of the same fundamental frequency but of predeterminedly different instantaneous amplitudes, said devicesin each said generating means having mutual cyclic relationships similar to those" of saiddevices. in each other said generatingmeans; and. control means, effective for a plurality of notes, for progressively varying the response of said lead means diiierentially with respect to the several said oscillation series.

5. In a musical instrument including key means ,and'oscillation-responsive load means: a plurality of continuously revolving capacitive generating means for respective notes of the musical scale, electrically interposed between said key and load means, each generating means com prising a plurality of devices for producing a respective plurality of complex oscillation series of the same fundamental frequency but of predeterminedly difierent instantaneous amplitudes, said devices in each said generating means hav-- ing mutual cyclic relationships similar to those of said devices in each other said generating means; and control means, efiective for a plurality of notes, for progressively varying the response of said load means differentially with respect to the several said oscillation series.

6. In a musical instrument including key means and oscillation-responsive load means: a plurality of continuously revolving photo-electric generating means for respective notes of the musical scale, electrically interposed between said key and load means, each generating means comprising a plurality of devices for producing a respective plurality of complex oscillation series of the same fundamental frequency but of predeterminedly difierent instantaneous amplitudes, said devices in each said generating 'mwns having mutual cyclic relationships similar to those of said devices in each other said generating means;

and control means, eiIective for a plurality of notes, for progressively varying the response of said load means differentially with respect to the several said oscillation series.

7. In a musical instrument including key means and oscillation-responsive load meansza plurality of continuously revolving generating means for respective notes of the musical scale, electrically interposed between said key and load means, each generating means comprising a plurality of devices for producing a respective plurality of complex oscillation series of the same fundamental frequency but of predeterminedly diiIerent instantaneous amplitudes, said devices in each said generating means having mutual cyclic relationships similar to those of said devices in each other said generating means; and control means, eflective for a plurality of notes,

for progressively varying the response of said lead means difierentially with respect to the several said oscillation series;

8. In a musical instrument including key means and oscillation-responsive load means: a plurality of continuously revolving generating means for respective notes of the musical scale, each comprising a plurality of devices for producing a respective plurality of complex oscillation series of the some fundamental frequency but of predeterminedly diiferent instantaneous amplitudes, said devices in each said generating means having mutual cyclic relationships similar to. those of said devices in each other said generating means and means for effecting activation. of said generating means, said activation being responsive to said key means and said lead means being responsive to said generating means; and control means, eiIective for apluralityot notes, for progressively varying the response of said load means differentially with respect to the several said oscillation series.

9. In a musical instrument including keymeans and oscillation-responsive load means; a plurality'of continuously revolving generating means for respective notes of the musical scale, electrically interposed-between said key and load means, each generating means comprising a plucontrol means, effective for a plurality of notes, for progressively varying the response of said load means differentially with respect to at least the amplitudes of the several said oscillation series.

10. In a musical instrument including key means and oscillation-responsive load means: a plurality of continuously revolving generating means for respective notes of the musical scale, electrically interposed between said key and load means, each generating means comprising a plurality of devices for producing a respective plurality of complex oscillation series of the same fundamental frequency but of predeterminedly different instantaneous amplitudes, said devices in each said generating means having mutual cyclic relationships similar to those of said devices in each other said generating means; and control means, effective for a plurality of notes, for varying the response of said load means differentially with respect to at least the phases of the several said oscillation series.

11. In a musical instrument including key means and oscillation-responsive load means: a plurality of continuously revolving generating means for respective notes, of the musical scale, electrically interposed between said key and load means, each generating means comprising a plurality of devices for producing a respective plurality of complex oscillation series of the same fundamental frequency but of predeterminedly different instantaneous amplitudes, said devices in each said generating means having mutual cyclic relationships similar to those of said devices in each other said generating means; and control means, effective for a plurality of notes, for varying the response of said load means differentially with respect to the amplitudes and phases of the several said oscillation series.

12. In a musical instrument including key means and oscillation-responsive load means: a plurality of continuously revolving generating means for respective notes of the musical scale, electrically interposed between said key and load means, each generating means comprising a pinrality of devices for producing a respective plurality of complex oscillation series of the same fundamental frequency but of predeterminedly different instantaneous amplitudes, said devices in each said generating means having mutual cyclic relationships similar to those of said devices in each other said generating means; and control means, effective for a plurality of notes, for selectively reversing the response of said load means to at least some of said oscillation series, in respect of phase.

13. In a musical instrument including key means and oscillation-responsive load means: a plurality of continuously revolving generating means for respective notes 'of the musical scale, electrically interposed between said key and load means, each generating means comprising a plurality of devices for producing a respective plurality of complex oscillation series of the same fundamental frequency but of predeterminedly different instantaneous amplitudes, said devices in each said generating means having mutual cyclic relationships similar to those of said defor selectively displacing the response of said load means to at least some of said oscillation series in a less than half-cycle phase respect.

14. In a musical instrument including key means and oscillation-responsive load means: a plurality of continuously revolving generating means for respective notes of the musical scale, electrically interposed between said key and load means, each generating means comprising a plurality of devices for producing a respective plurality of complex oscillation series of the same fundamental frequency but of predeterminedly different instantaneous amplitudes, said devices in each said generating means having mutual cyclic relationships similar to those of said devices in each other said generating means; and control means, associated with the output of said generating means and effective for a plurality of notes, for progressively varying the response of said load means differentially with respect to the several said oscillation series.

15. In a musical instrument including key means and oscillation-responsive load means: a plurality of continuously revolving generating means for respective notes of the musical scale, electrically interposed between said key and load means, each generating means comprising a plurality of devices for producing a respective plurality of complex oscillation series of the same fundamental frequency but of predeterminedly different instantaneous amplitudes, said devices in each said generating means having mutual .cyclic relationships similar to those of said devices in each other said generating means; means for effecting activation of said generating means; and means, associated with and influencing said activating means and effective for a plurality of notes, for progressively varying the response of said load means differentially with respect to the several said oscillation series.

16. In a musical instrument including key means and oscillation-responsive load means: a plurality of continuously revolving generating means for respective notes of the musical scale, electrically interposed between said key and load means, each generating means comprising a plurality of devices for producing a respective plurality of complex oscillation series of the same fundamental frequency but of predeterminedly different instantaneous amplitudes, said devices in each said generating means having mutual cyclic relationships similar to those of said devices in each other said generating means; and control means, mechanically associated with said generating means-and effective for a plurality of notes, for varying the response of said load means differentially with respect to the several said oscillation series.

17. In a musical instrument including a plurality of keys, oscillation-responsive load means,

and a plurality of generating means for different fundamental frequency oscillations: switch means controlling the response of said load means to said oscillations and comprising a plurality of poles individually associated with said keys, and a common resistive contact member transverse of said poles and progressively contacted, as any of said keys is depressed, by the pole associated with that key.

BENJAMIN F. MIESSNER. 

